Automatic telephone exchange



July 7, 1925.

F. A. LUNDQUIST AUTOMATIC TELEPHONE EXCHANGE Original Filed March 2 19 ,21

Patented July 7, 1925. 1,

UNITED STATES FRANK A. LUNDQUIST,

OF CHICAGO, ILLINOIS, ASSIGNOR, BY KIESNE ASSIGNIEN'IB,

TO HENRY S. CONRAD, TRUSTEE.

AUTOHATIC TELEPHONE EXCHANGE.

Application filed latch 28, 1921, Serial No. 456,061. Renewed December 12, 1924.

mechanism is designed to move first in' one direction and later in a second direction to make a telephone connection. The rectan gular arrangement of :the contact oints is not shown, as such things are wel known,

and only part of the switch moving mechanism is shown as the present inventlon resides in other'matters. -5

The accompanying drawing 1s a diagram showing the central oilice arrangement for three switching mechanisms representing subscribers stations No. 11, No. 44 and No. 55. Each switching mechanism is provided with wires 15 and 16 which extend to the corresponding local stations. The mechanism involved will be understood by a description of the operation, which will assume that the subscriber at station No. 11

' is calling the one at station No. 44.

When subscriber at station No. 11 removes his receiver, his wires 15 and 16 are con nected together in the ordinary manner; When this occurs a current flows :-batteryX14-15 local st-ation16-17- 181920212223ground-X.

This attracts armature 24 to open valve 25 and permit valve 26 to close. These valves, and the other valves to be mentioned, are check valves which are normally closed but which are opened when their projecting pins are pushed inward. A valve of this character has been illustrated in detail in my pending application, Serial No. 244,731, filed July 13, 1918, and also in other pending applications.

The opening of valve 25 permits compressed air to flow from the general supply pipe 27 thru'the pipe 28 to the sylphon 29.

This sylphon is a motor of the compound diaphragm type and serves to move lever 30 on its pivot 31. The pipe'28 has a leaky check valve 32 which permits a rapid flow of air to sylphon 29 when valve 25 is opened, but retards the exhaust when this valve is closed. The result of this arrangement is that if the valve 25 is opened and closed rapldly several times in succession, the'sylceeding because the check valve '32 revents 'phon remains expanded during such vpro- I air becoming exhausted during t e brief period between one opening and the next of the valve 25. Butif thevalve 25* remains closed for a period somewhat longer than those which intervene between the pulsations herein used, then sylphon 29 contracts. This sylphon is a slow motor which corresponds to the slow relays known in automatic telephony.

The movement .of lever 30... ju'st described permits spring 33 to move '7 open valve 35 and perm the source thru pipe 36 jto flow from valve 26. But

as valve 26 was closediibyf -the previous atv tract-ion of armature --24,'"nothing occurs as the result of this action beyond extendingv the air pressure to valve 26.

The lower end of lever 30 is connected by means of link 37 withthetail of a pawl 38 pivoted at 39 on a slide"40. Adjacent to the pawl 38 is a channel 41'having pivoting pins 42 on its ends. On opposite flanges of channel 41 are teeth arranged. to be engaged by pawl 38. The long teeth are those on the near side of the channel, and the short teeth are those on the far side. The

spacing of those teeth longitudinally on the channel is that shown in the drawing.

From the valve 26 a pipe 43, with check valve 44 therein, extends to sylphon 45, andfrom this a rod 46 extends to channely41. The sylphon 45 is a slow 'motor, and the connections are such that the expansion and contraction of the sylphon 45 rock the channel 41 on its pivots so that said channel becomes an escapement for pawl 38 when said pawl is under tension from sylphon 29.

When the sylphon 29 expands as before described, it turns pawl 38 on its ivot until the tail of the pawl strikes the adiacent lug on slide 40. When this occurs, the slide is moved to the right until stopped by the pawl engaging tooth 47 on channel 41. This is the condition which automatically occurs as the result of the calling subscriber removing his receiver from its hook.

The next thing the subscriber does is to operate his dial in the ordinary manner,

which results in breaking and immediately remaking the circuit thru his magnet 1417. This will occur once or a plurality of times according to what digit he is indicating by his dial operation. The circuit is that previously described.

' In the present instance, the subscriber breaks and remakes this circuit four times which results in giving four full vibrations to the armature 24, and this in turn results in closing and reopening the valve 25 four times, and in opening and reclosing the valve 26 the same number of times. The operation of valve 25 affects nothing, because the check 32 prevents air from becoming exhausted from sylphon 29. That sylphon continues to appl strain to slide 40 to move it toward the rig t. The operation of valve 26 causes sylphon 45 to expand, to remain expanded during-the operations of the valve, and to contract upon the termination of the operations of said valve. The expansion of sylphon 45 turns channel 41 to permit pawl 38 to advance from tooth 47 to tooth 48, and the contraction of the sylphon permits further advance from tooth 48 to tooth 49.

From the pipe 43, between valve 36 and check 44, is a branch pipe 50 which leads to a motor 51. This motor is connected to and operates switch moving mechanism arbitrarily illustrated at 52. This mechanism moves wipers first in one direction and later in another direction after the manner illustrated in my pending application, Serial No. 253,156, filed September 9, 1918.- Devices for moving the mechanism in only one direction is shown because the structure and operation of this mechanism is no part of the present invention. As there is no check valve in pipe 50, the motor 51 responds by as many reciprocations as there are pulsations in pipe 43 by reason of opening and closing valve 26.

When the subscriber begins on the second series of impulses by the operation of his dial, sylphon 45 is expanded to permit pawl 38 to advance from tooth 49 to tooth 53, and when the impulses cease, sylphon 45 contracts to permit a further advance to tooth 54. This is the position at which slide 40 is when the wipers of the moving mechanism reach the bank contacts of the subscriber to be called.

In this position the insulation on the lower face of slide 40 engages the spring 19 and moves it from spring 20 to spring 55. This breaks the previously described circuit for magnet 1417. When the subscriber removed his receiver and caused his slide 40 to advance till pawl 38 engaged tooth 47, this movement 0 the slide permitted spring to move from 62 to 61. If subscriber No. '44 had removed his receiver before No. 11 had moved his switching mechanism to the terminals of N0. 44, then the previously defollows :195556-575859 of No.

4460- 61ground. Under the conditions ust described, the movement of spring 19 from spring 20 to s ring 55 is simply substitutingone groun connection for another and not breaking the circuit for magnet 14 -17. If the circuit is not broken thru magnet 1417 by reason of a ound connection having been found at 0. 44, then the apparatus of No. 11 will stand with slide 40 depressing ring 19.

In this position 0 the slide, the head 63 thereon connects busy tone with the subscribers lines 15 and 16 thru the condensers 64. Also in this sition of the slide, a pin or roller 65 on ever 30 engages another lever 66 so as to open valve 67 and permit air to flow to a sylphon 68. In the pipe between valve 67 and sylphon 68 is a check or other restraining device 69 so constructed as to retard the flow of air toward sylphon 68 and consequently make that motor slow to act. If the slide 40 is quickly advanced so that head 63 does not remain in connection with busy tone, then pin 65 quickly leaves lever 66 and the consequent opening of valve 67 is without effect. If, however, the slide stands at busy position, then the expansion of sylphon 68 pushes pin 70 under sylphon 45 so as to prevent that sylphon rocking the channel 41 to permit a further advance of slide 40. The object of this is to prevent the head 63 being advanced to talking position when the associated wipers come upon the terminals of a busy line.

The calling subscriber, upon hearing the busy tone, replaces the receiver on the switchhook thereby opening the circuit for magnet 14-17 at the substation which causes the deenergization of said magnet. Upon the deenergization of magnet 14-17, armature 24 returns to normal position and closes valve 25 which cuts off the supply of air from sylphon 29. Another result caused by the operation of armature 24 returning to normal position is the opening of valve 26 which causes an impulse of air to flow to motor 51 and sylphon 45. The impulse of air to sylphon 45 is without result as the pin 70 prevents the rocking of channel 41, and the impulse to motor 51 is also with effect as the wipers are disconnected from any battery or ground connectlons.

After a pre-determined interval sylphon 29 returns to normal position, and closes valve 67 to allow the slow operating sylphon. 68 to return to normal position. Sylphon 29 on its return to normal position also closes valve 35 which valve cuts the air connections from the sylphon 45 and motor 51. When the air from sylphon 29 is finally advance from tooth 54 to tooth 71.

pawl 38 is caused by sylphon 29- exhausted, the slide 40, pawl 38" and theother motors allows the wipers and mecha-' nism to return to'normal position.

Returning now'to the arrival ot the sl de 40 to the position at which the insulation 'on the slide moves spring 19 from spring 20 to spring 55, if the subscriber to be called is busy, then the slide stands at that cs1- tion and the calling subscriber gets the usy signal. But if the sulEcriber to be called is not busy, then this movement of the sprin 19 breaks the circuit for magnet 14-1 and armature 24 falls back. This admits air to sylphon 45 which turns chan-.

nel 41 on its pivots to permit pawl38 to The advance of on which a1r pressure is still maintained by check valve 32,

This is a long step which releases spring 19 so that it returns to engagement with spring 20, depresses spring 76 to engagement with spring and brings head 63 to the position in which it connects the ringing generator to the called line. Releasing spring 19 again closes the'circuit for magnet 14-17 which results in the pawl advancing from tooth 71 to tooth 72. This is a short step which aifects nothing. Depressing spring 76 completes a circuit as follows: X at switch No. 44737 46260-59 58-575 67576groundX'.

This circuit thru the coil 73 attracts armature 77 to break the connection between springs 22 and 23 at thecalled switch, and consequently the circuit for the magnet 1417 of the called switch so that the ringing impulses going to the local station of the called subscriber will not afl'ect that magnet. The ringing circuit is as, follows :-generator 63-line 78 at switch No. 1179-80-81-8283-8415-local sta tion 16 8687-88-89-9O 63- generator. There is a branch of this thru line 91 and coil 92 at the calling switch, but the armature 77 is sluggish and does not respond to the cycles used in ringing.

When the called subscriber removes his receiver he connects his lines 15 and 16 directly together which results in completing a circuit as follows :-X at switch No. 11-73-7463-ringing circuit -just described9l92-groundX.

This attracts armature 77 and breaks the circuit for magnet 1417, which results as before in an advance by slide 40, the pawl going from tooth 7 2 to tooth 93. This carries the head 63 from the ringing generator to the talking position and breaks the circuit for magnet 7392 of No. 11 at 74 and 91, and the circuit for magnet 73-92 of No. 44 at springs 75 and 76 at No. 11.

These actions permit springs 22 and 23 of both switches to close so as to complete circuits for ma At No. 1-1 this'results in a short movement to-the last tooth on the channel 41, which movement affects nothing. At No. 44 the slide'40 is moved 011' normal so as to shift spring 60 from 62 to 61.

The talking circuit may be readily traced from lines 15 and 16 of No. 11,. thru the condensers 64, the head 63 and the ringing circuit reviously described;

On t e termination of conversation, the called subscriber replaces his receiver on the switchhook, thereby breaking the circuit for magnet 14- 17. The breaking of the circuit for magnet 14-17 of the called switch closes the valve 25 and al ows sylphon 29 to return to normal positlon, and in so doing returns the slide 40 and circuit closing head to normal position. The calling subscriber upon hanging up his receiver breaks the circuit for the magn switch, thereby allowing the switch to release inthe manner. previously described.

Reviewing the operations, it will be seen that when a calling subscriber removes his receiver he puts his slide 40 under a tension which advances it to engagement with a tooth on an escapement. When the subscriber mani ulates his dial to cause an operation of iiis switching mechanism, the

ets 1417 of both switches.

et 14-17 of the calling slide advances by two stages to another tooth on the escapement. When the subscriber manipulates his dial the second time to bring his wipers on the terminals of a station to be called, the slide is advanced to a third tooth, in which movement the slide carries a head or bridging contact maker 63 to a position which connects the lines of the calling subscriber to busy tone contacts, and also shifts a spring in the circuit of the magnet used in controlling the operations. The circuit connections for this spring are such that if the subscriber to be called is busy, then the slide is held with the head on busy tone, but if the subscriber is not busy then the slide is automatically and promptly advanced to a fourth position to connect the called subscriber to the ringing generator. When the called subscriber removes his receiver he completes a circuit for the control magnet by which the slide is advanced .to a

successive circuit closing positions. Each brealt and remake advances the head on a long step to shift its connectlons or a short stop for setting the apparatus without affooting the connections made by the head.

The arrival of the wipers at the terminals of the subscriber to be called is coincident with the arrival of the head at busy tone and the breaking of the circuit at 19 to cause an immediate advance of the head to the ringing connection. The arrival of the head at the ringing position closes the c1rcu1t at 76 for the cut oil relay at the called switch and prepares the circuit for the cut oil relay at the calling switch thru contacts closed by the head. Response by the called subscriber completes the circuit for the cut off relay at th calling switch and this in turn operates the control magnet to advance the head to talkng position. This last advance breaks the circuit for both relays.

Returning now to the arrival of the wipe-rs at their final position, it was shown that No. 11 would get the busy signal by magnet 1417 finding ground at 61 if No. 44 had moved his mechanism from normal position. But No. might have called No. 44 earlier, and No. 11 may. have come upon the previously occupied line before N o. 44 hadremoved his receiver. In the condition in which No. 55 has called N0. 44 and No. 44 has not yet removed his receiver, No.55 is at ringing position with his spring :76 depressed. Under this condition the circiiit for magnet 14-17 does not go from bank wire 58 to 59 of No. 44, but to wiper 57 of No. 55-567576gr0und.

Referring back to the operation, it is to be observed that theswitching mechanism is advanced each time the magnet 1417 attracts its armature, and also each time the armature is retracted. These advances are divided into short steps which are settingor preparatory steps, and long steps which are operating steps. In the adjustment of the wipers 57, 79 and 89, the long steps come as a result of attracting the armature. In the adjustment of the head 63, the long steps come as a result of retracting the armature.

That I claim is:

1. A circuit closing head and a pneumatic device for moving it by successive steps to busy, ringing and talking positions, and means by which eachmovement of said head is controlled thru connections made by the next preceding movement. I

2. A circuit-closing head, a pneumatic device for moving it step by step to busy, ringing and talking positions, amagn'et for controlling said device, a circuit for said magnet, and means by which the steps of said magnet are controlled by interrupting said circuit successively at different places therein.

3. A circuit-closing head a pneumatic device for moving said he an escapement net controlling such movements, and means for controlling the magnet thru connections made by the movements of the head.

5. A series of switching mechanisms, a magnet, a relay and a circuit-closing head at each mechanism; pneumatic motors controlled by each magnet for controlling the movements of its associated head; and means by which a moved head controls circuits for relays at two switching mechanisms.

6. In the switching apparatus of an automatic telephone exchange, wipers and mechanism for moving them step by step to a desired position, a circuit closing head and mechanism for moving it step by step to test, ringing and talking positions, a magnet and a relay associated with said mechanisms, and circuit connections thru which said magnet and said relay acting individually and conjointly serve to completely control all operations of said mechanisms.

7. The combination with a switching mechanism having pneumatic motors for moving said mechanism, and a control magnet arranged to control "aseries of opera tions of said mechanism and arranged to control the movement of said mechanism from normal to busy position, of a relay arranged to control only the first operation of said magnet and only one of said series of operations.

8. The combination with a switchingmagnet operated as a stepping relay in response to electrical impulses and as a test magnet over a circuit including said station.

10. The combination with a switching mechanism, pneumatic motors arranged to move said mechanism to make telephonic connections, lines leading to alocal station, and a switch controlling. magnet operated over said lines for controlling said motors, of means thru which said magnet serves as a'stepping relay to actuate said mechanism ture and another part to and as a test magnet to determine whether adesired connection is or is not busy.

ll. The combination with a switching mechanism arranged to be moved by pneumatic motors thru a series of adjustments to complete a telephonic connection, of a magof said devices is controlled thru attractions of said armature, and means by which the movements of the other of said devices is controlled thru rctractions of said armature.

13. The combination with a switching mechanism to be moved, and a magnet and armature for operating pneumatic motors for controlling such movements, of a reversing device arranged to cause a part of such control to be thru attractions of said armabe thru retractions of said armature.

l4. he combination mechanism and power devices for moving it, of an escapement arranged to control such movements by the vibration of a part thereof, said vibrating part being so constructed that the movement of the mechanism will be by alternate short and long steps for a plurality of steps and will then reverse so that the movement will thereafter be by alternate long and short steps for another'plurality of steps.

15. The combination with a switching mechanism and power devices for moving it, of a controlling device arranged to cause such movements to be by alternate steps of with a switching difl'erent lengths, said device being so constructed that at one point two steps of the same length follow each other so that thereafter the order of long and short steps will be reversed.

1G. The combination with a switching mechanism and means for moving it, of means by which such movements begin by alternating short and long steps and ends by alternate long and short steps.

17. The combination with telephonic connecting devices and pneumatic motors for moving them, of an escapement by whic' suchmovement is divided into two stages in which the second automatically follows the first, a locking device, and means by which a relay in a shift from the first stage to the second will bring said locking device into action to prevent the second stage occurrin 18. The combination with switching devices, pneumatic devices for moving the switching devices, and means for controlling said devices, of means for shifting the 1' lationship of the control to the movement of an intermediate stage of such movement, and pneumatic motors arranged for operating a locking device to prevent further movement when delay occurs in such shift.

19. In an electro-pneumatic system,wipers, a pneumatic motor for moving said wipers to a desired position, a circuit closing head and a pneumatic device for moving it by successive steps to busy, ringing and talking positions, and a control magnet serving first to control the operations of said motor and later to control the movements of said circuit closing head.

20. In a switching mechanism, pneumatic motors for operating sa1d mechanlsm, a control magnet, a relay which serves to prevent ringing connections from eauslng the operation of said magnet and later serves to cause the operation of said magnet to cause the operation of said mechanism. p

FRANK A. LUNDQUIST. 

